Manufacturing of semiconductor devices typically involves performing a sequence of procedures with respect to a substrate such as a silicon substrate, a glass plate, etc. (Such substrates may also be referred to as wafers, whether patterned or unpatterned.) These steps may include polishing, deposition, etching, photolithography, heat treatment, and so forth. Usually a number of different processing steps may be performed in a single processing system or “tool” which includes a plurality of processing chambers. However, it is generally the case that other processes are required to be performed at other processing locations within a fabrication facility, and it is accordingly necessary that substrates be transported within the fabrication facility from one processing tool to another. Depending upon the type of semiconductor device to be manufactured, there may be a relatively large number of processing steps required to be performed at a considerable number of different processing tools/locations within the fabrication facility.
It is conventional to transport substrates from one processing location to another via substrate carriers such as sealed pods, cassettes, containers or open trays or cassettes and so forth. It is also conventional to employ automated substrate carrier transport devices, such as automatic guided vehicles, overhead transport systems, substrate carrier handling robots, etc., to move substrate carriers from tool to tool within the fabrication facility or to transfer substrate carriers from or to a substrate carrier transport device.
For an individual substrate, the total device fabrication process, from formation of the substrate to cutting of individual semiconductor devices from the finished substrate, may require an elapsed time that is measured in weeks or months. Accordingly it would be desirable to reduce substrate transfer time in an effort to reduce non-value added time.